Eur. Phys. J. B 9, 15-20 (1999)
https://doi.org/10.1007/s100510050737

^69.71Ga-NMR study of the low-energy excitations in NdGa₂

¹ Laboratorium für Festkörperphysik, Eidgenössische Technische Hochschule-Hönggerberg, 8093 Zürich, Switzerland
² Tokyo Metropolitan University, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397, Japan

Received: 3 September 1998
Revised: 3 November 1998
Published online: 15 May 1999

Abstract

We report the results of ⁶⁹Ga- and ⁷¹Ga-NMR measurements on NdGa₂ at temperatures between 0.1 and 3 K and in applied magnetic fields between zero and 74 kOe. NdGa₂ orders antiferromagnetically below 9.5 K and undergoes several metamagnetic transitions in external magnetic fields. In zero applied magnetic field and below 1 K the temperature dependence of the spin-lattice relaxation rate shows a large linear-in-T term, about two orders of magnitude higher than for the reference compound LaGa₂. This strong enhancement confirms the presence of low-energy excitations in the antiferromagnetic phase of NdGa₂ as was previously indicated by specific heat data. Above 1 K, is dominated by an exponential term, which we associate with excitations between the lowest energy levels of the f-electron system. The separation of these energy levels is determined by exchange, crystal-field and Zeeman interactions.